Passive radar technology is used for detection of motion and positioning of targets by analyzing how transmitted signals from third party radio signal sources change over time. The third party radio signal sources may for example be constituted by broadcasting of television and radio, wireless communication networks such as for example GSM.
WO2009/128002 discloses a passive detector for determining presence or motion in an environment. The detector includes a receiver with a channel estimation module configured to determine a best channel to be monitored. A monitor is configured to measure fluctuations in the best channel
However, there is still a need for a motion detector that improves the reliability of the detection process.